The present invention relates to a data transfer control device, an electronic instrument, and a data transfer control method.
The Universal Serial Bus (USB) 1.1 standard defines a data transfer rate of 12 megabits per second (Mbps) (full-speed (FS) mode) required for various peripheral devices of personal computers, and a data transfer rate of 1.5 Mbps (low-speed (LS) mode) aiming at connection with less expensive peripheral devices. In recent years, the USB 2.0 standard has been developed and has attracted attention as a standard which can achieve a data transfer rate of 480 Mbps (high-speed (HS) mode), which is remarkably higher than the data transfer rate of the USB 1.1 standard, while having compatibility with the USB 1.1 standard.
The market for products conforming to the USB 2.0 standard which supports the HS mode has grown steadily. The USB On-The-Go (OTG) standard has been developed by the USB Implementers Forum (USB-IF) as a standard which realizes a simple host of the USB standard. The OTG standard (OTG 1.0) developed as an extension of the USB 2.0 standard has the potential for creating a new added value for the USB interface, and development of applications making use of its characteristics has been anticipated.
A peripheral (peripheral device), which has been connected with a host (personal computer or the like) through the USB, can be provided with the host function by utilizing the simple host realized by the OTG standard or the like. This enables data to be transferred between peripherals by connecting the peripherals through the USB. For example, an image from a digital camera can be printed by directly connecting the digital camera with a printer, or image data or video data can be saved by connecting a digital camera or a digital video camera with a storage device.
It becomes unnecessary to connect the peripheral with the host through the USB by utilizing the simple host realized by the OTG standard or the like. Therefore, this technology is expected to be applied to portable instruments driven by a built-in battery. Therefore, it is important to reduce power consumption of data transfer conforming to the USB standard and to effectively use the transfer band.